Objectives: Cow's milk protein hydrolysate formulas are widely used for genetically predisposed atopic infants. Whether hydrolysate formulas can induce oral tolerance to alpha-casein was studied for the first time in naive and sensitized mice.
Methods: Using immunoblotting, residual antigenicity to alpha-casein was examined for in animals fed hydrolysate formulas. Naïve mice fed hydrolysate formulas for 1 to 4 weeks were later sensitized with alpha-casein. Another group of mice sensitized first with alpha-casein were then fed hydrolysate formulas continually for 12 weeks.
Results: Oral tolerance measured by immunoglobulin (Ig)E and IgG1 antibody responses to alpha-casein was induced in naïve mice fed NAN for 1 week or NAN-HA for 4 weeks. IgE responses to alpha-casein were suppressed in mice fed NAN-HA for 1 week or Neoangelac FL for 4 weeks. In contrast, mice fed Alfare, Pepti-Junior, or Pregestimil for 1 to 4 weeks did not develop tolerance to alpha-casein. Antibody responses to alpha-casein were not significantly suppressed in sensitized mice fed NAN or hydrolysate formulas for 12 weeks.
Conclusions: Primary IgE responses to alpha-casein are readily suppressed in naïve mice first fed cow's milk formula or partially hydrolyzed formula for 1 week. Conversely, ongoing IgE, IgG1, and IgG antibody responses to alpha-casein are poorly suppressed in previously sensitized mice even after prolonged feeding of cow's milk formula or hydrolysate formulas.